Housing for portable machines



Nov. 18, 1969 E. c. HINCK m, ET A-L 3,473,958

HOUSING FOR PORTABLE MACHINES Filed Jan. 11, 1968 2 Sheets-Sheet lINVENTORS ERNEST 6. H/NCK 111 JOHN Z BOWEN ATTORNEY 1969 E, c. HINCK m,ETAL 3,473,958

HOUSING FOR PORTABLE MACHINES Filed Jan. 11, 1968 2 Sheets-Sheet 3 A 1 ma l i v f (Fi l FIG. 3

' INVENTORS Q8 ERNEST a. H/NCKIUI JOHN r BOWEN ATTORNEY United StatesPatent 3,478,958 HOUSING FOR PORTABLE MACHINES Ernest C. Hinck III,Skillman, and John T. Bowen, Princeton, N.J., assignors toIngersoll-Rand Company, New

York, N.Y., a corporation of New Jersey Filed Jan. 11, 1968, Ser. No.697,106 Int. Cl. F04b 39/00 US. Cl. 230-232 Claims ABSTRACT OF THEDISCLOSURE A housing for a portable machine such as a compressor whichis designed to muffle the noise produced by the machine. The housingincludes a shell having a base, sidewall end walls and a top. A pair ofducts, parallel to the sidewalls conduct cooling air from outside theshell to the inside of the shell. A fan driven by the engine blows theair through a radiator system and through a chamber in which thecompressor and compressor engine are housed. The cooling air then flowsinto a second or exhaust duct having its inlet at the opposite end ofthe shell from which it exits to the outside of the shell. Doors areprovided in the housing to permit access to the machine. Each of thewalls is covered with a sound absorbing material.

BACKGROUND OF THE INVENTION This invention relates to housings forportable machines and in particular to a housing whichmuffies the noiseproduced by a machine such as a portable compressor.

It is well known that when construction work is being done, the noiseproduced by the various machine used in such construction work isdisturbing to people in the vicinity of such work. This is particularlytrue when the work is being done in a populated area. Much of this noiseis produced by the portable compressor and in particular the engine usedto drive such portable compressor. The noise level has been measured atover 115 decibels. City ordinances often require that noise level belower than 90 decibels at a certain distance. Although these ordinancesvary from city to city, the noise produced by most present day machinesis well above the noise level requirements of these ordinances.

Attempts have been made to reduce the sound level of these machines butmost of them have been unsuccessful..The addition of ordinary exhaustmufliers to the engine does reduce the noise level, but the machinenoise still exceeds a desirable level. Of the methods tried, there aretwo principal disadvantages. The primary disadvantage is that themachine overheats due to lack of proper ventilation. If sufficientcooling air is provided, the noise level is not adequately reduced. Asecond disadvantage is that the unit becomes so large that it is nolonger easily moved from job to job.

One prior arrangement includes a tent which is placed around thecompressor. As is well known, tents do not have much ventilation. Thislack of ventilation leads to overheating of the machine. If suflicientopenings are provided to permit adequate cooling, the noise travelsthrough the openings and the level of sound is not adequately reduced. Asecond method of reducing noise level is to completely enclose themachine with the exception of the end where the engine fan is located.At this end a honeycomb mufiling system is added. In order to beeffective, this honeycomb arrangement is adequate for small machines butif this arrangement is used on large machines, the length of thehoneycomb must be such that the machine is no longer portable.

SUMMARY It is therefore the principal object of this invention toprovide a mufliing system for a machine which permits adequateventilation of the machine.

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It is a further object of this invention to provide apparatus whichmufiles the noise produced by a machine yet does not increase the sizeof the unit to an extent where it is no longer portable.

In general, these and other objects are carried out by providing ahousing for muflling the noise produced by a machine comprising: a shellsurrounding a machine; first duct means having an inlet and an outlet,said outlet communicating with the inside of said shell at one end ofsaid shell for conducting air for cooling said machine from outside thehousing to the inside of said shell; said first duct means beinggenerally U-shaped and mounted on said shell 50 that its legs extentdover at least a portion of the sides of said shell and beingsufliciently long to mufile the sound produced by said machine whichtends to travel through the duct; said shell being provided with anexhaust opening near its other end for conducting air out of the shell.

BRIEF DESCRIPTION OF THE DRAWINGS This invention will be described inconnection with the following drawings wherein:

FIG. 1 is a perspective view of the housing of this invention with partsbroken away for purposes of clarity;

FIG. 2 is a sectional view of the embodiment of FIG. 1 with a compressorshown in broken lines;

FIG. 3 is a sectional view of some of the walls of the housing of thisinvention;

FIG. 4 is a sectional view of other walls of the housing of thisinvention; and

FIG. 5 is a perspective view of a modification of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, inFIG. 2 there is shown in broken lines a compressor generally indicatedat 1 powered by an engine 2. The compressor includes air intakes 3 andfilter 4. In addition to the compressor, the engine drives a suitablefan 5 and radiator system. A mutfier 6 connected to the engine exhaustis positioned in the housing. The outlet of the compressor is connectedto a receiver 7 in a conventional manner. If desired, the receiver 7 maybe covered with a sound absorbing material. The unit is mounted onwheels 8 to provide portability.

Referring now to FIG. 1, the housing is generally indicated at 10. Thishousing includes a base 11, a pair of sidewalls 12 and 13, a pair of endwalls 14 and 15 and a top 16. A top wall 20, parallel to the top 16 ofthe housing 10, is mounted within the shell 10 and extends across theentire width of the housing. At the-forward end of this top wall thereis provided an opening 21. A pair of wall means 23 and 24 extenddownward from the top wall 20 to the base 11 to define with the top wall20 a shell surrounding the engine and compressor. The shell means isprovided with an inlet at one end in which the fan 5 is mounted and anoutlet 21 at its other end.

A first duct means is provided for conducting air for cooling the engineand compressor from outside the housing to the inside of the shell. Thefirst duct means is generally U-shaped and includes a base defined bythe end wall 15 which provides an outlet communicating with the inlet ofthe shell. The legs of the first duct means are defined by the sidewalls 12 and 13, wall means 23 and 24 and the top wall 20 to providepassages 27 and 28 having inlets 29 and 30, respectively. In theembodiment of FIG. 1, the legs of the first duct means extend the entirelength of the shell.

A second duct means 31 is defined by the top 16, sidewalls 12 and 13 andthe top wall 20 to provide a passage 31. The second duct means has anoutlet 22 and an inlet communicating with the exhaust or outlet 21 ofthe shell.

When the machine is operating, the fan 5 draws cooling air through theinlets 29 and 30 of the first duct means and through passages 27 and 28and around an arcuate portion 35 in the end wall 15 making a 180 turnand through the radiator and fan into the shell. Cooling air flows allaround the engine 2 and compressor 1 providing adequate ventilation.From the engine-compressor chamber, air fiows through the exhaustopening 21 making a 180 turn and out the duct 31 to the duct outlet 22where it exhausts to atmosphere.

Two important features are the cross sectional area of the passages 27,28 and 31 and the length of these passages. The cross sectional areadetermines the amount of air flow and thus the amount of ventilation.The amount of sound reduction. The ducts should be sufficiently long tomutlle the noise produced by the machine which tends to travel throughthe ducts. If these ducts were short, it would provide a short passagefor noise to travel out of the inside of the shell. Although in generallonger ducts mean more sound dampening, there is a point whereincreasing the length of the ducts no longer reduces the noise level.The wrap around design of the cooling air ducts permits a reduction inthe overall size of the machine when compared with normal silencingtechniques. In addition, the wrap around design provides a double-walledarrangement which further reduces noise transmission through the shell.

In FIGS. 3 and 4, the construction of the walls can be seen. The outerwalls are preferably constructed in accordance with FIG. 3. Each ofthese Walls including a supporting base member 40 which may be sheetmetal. On the inside of this sheet material there is a suitable soundabsorbing material 41 such as fiber glass. This insulating material isthen covered with a suitable screening 42 in order to insure that theinsulating material will not shred. In FIG. 4 the base material 40 issandwiched between two layers of insulating material and two layers ofscreening. This particular wall construction insures that there isadequate sound absorption by the housing. The double wall constructionof FIG. 4 is used in top wall 20 and inside walls 23 and 24 to insuresound deadening in both the motor and compress-or chamber and the ducts27, 28 and 31.

In order to provide access to the working parts of the machine, thehousing of FIGS. 1 and 2 is provided with a double door arrangement. Thesidewalls of the housing are provided with doors 50 while the walls 23and 24 are provided with doors 51. In order to permit access to thefilters 4, suitable port holes and covers 52 have been provided. Thecontrols for the machine may be mounted inside the housing or on asuitable panel outside of the housing, whichever is preferred. Allexposed parts are preferably cushion mounted so that vibrations will bereduced.

In FIGURE 5 there is shown a modification of the housing of thisinvention. In this embodiment, the legs of the first duct means havebeen shortened and the second duct means has been removed. In thisembodiment, the housing includes a shell, generally indicated at 60which surrounds a compressor and engine. The first duct means 61 isgenerally U-shaped and is substantially the same as that shown in theembodiment of FIG. 1 except that the legs have been shortened so thatthey do not extend the entire length of the housing. The first ductmeans 61 is provided with inlets '62 and an outlet for conductingcooling air to the inside of the shell.

The shell 60 is provided with an exhaust opening 63 at the end oppositefrom the inlet of the shell. The location of the outlet in the top ofthe shell insures proper air flow through the shell. A hinged cover 64is mounted on the top of the shell so that the opening 63 may be closedwhen the compressor is not in use.

In order to insure proper silencing, the entire machine of theembodiment of FIG. 5 is enclosed in the shell 60. The mufilers and thecompressed air receiver are enclosed in the forward end of the shell.The mufflers exhaust through pipes 65 in the top of the shell. A pair ofpassages 66 are provided in one end of the shell to permit air to becompressed to reach the inlet of the compressor. Doors 67 and 68 areprovided in the shell to permit access to the compressor and engine.

Using the housing of FIGS. 1 and 2, the noise level of one unit wasdropped approximately 20 decibels when compared with a conventionalmachine. With a standard portable compressor, the noise level at 3 feetwas approximately dba. When the same compressor was placed in thehousing of FIG. 2 and operated at the same speed, the noise level at 3feet was approximately 82 dba. Although a noise level reduction of 10*dba. may be achieved with the use of proper muffiers and cushionmountings, the reduction of 20 dba. heretofore proved difiicult.

With the embodiment of FIG. 5, the noise reduction was somewhat less dueto the shortening of the side ducts and the lack of a top duct, butfound to be adequate for most uses. The embodiment of FIG. 5 does,however, provide the advantage of lower height, reduced cost ofmanufacture and easier accessibility to the machine.

Although but two prefererd embodiments have been described, it isintended that the invention be limited solely by that which is withinthe scope of the appended claims.

We claim:

1. For use in combination with a machine, a housing for mufilling thenoise produced by the machine comprising:

a shell adapted to surround a machine;

first duct means having an inlet and an outlet, said outletcommunicating with the inside of said shell at one end of said shell forconducting air for cooling said machine from outside the housing to theinside of the shell;

said first duct means being generally U-shaped and mounted on said shellso that its base is substantially coincident with one end of said shelland its legs extend over at least a portion of the sides of said shelland being sufliciently long to mufiie the noise produced by the machinewhich tends to travel through the duct;

said first duct means having its inlet in its legs and its outlet in itsbase;

said shell being provided with an exhaust opening near its other end forconducting air out of the shell.

2. The combination of claim 1 wherein said exhaust opening is positionedin the top of said shell, said housing further comprising a hinged coverfor selectively closing said exhaust opening.

3. In the combination of claim 1, said housing further :comprisingsecond duct means having an inlet communicating with said exhaustopening and an outlet and being sufliciently long to mufiie the noiseproduced by said machine which tends to travel through the duct.

4. The combination of claim 3 wherein the legs of said first duct meansand said second duct means extend the entire length of said shell andsaid second duct means forms the top of the housing.

5. The combination of claim 4 wherein said shell and said first andsecond duct means are made of sound insulating material.

6. An air compressor comprising:

a frame;

means for supporting said frame;

air compressing means supported by said frame;

an engine supported by said frame for driving said air compressingmeans;

a shell surrounding said machine for mufliing the noise produced by saidengine and air compressing means and having an inlet one end and anoutlet at the other end;

first duct means having an inlet and an outlet and mounted on said shellso that it extends over at least a portion of at least one side of saidshell; and

fan means powered by said engine mounted adjacent the inlet of saidshell for blowing air for cooling said engine and air compressing meansfrom the outlet of said first duct means into said shell.

7. The compressor of claim 6 wherein said first duct means is generallyU-shaped with the base covering the inlet of the shell and the legsextending over at least a portion of the sides of the shell.

8. The compressor of claim 7 wherein the outlet of said shell ispositioned in the top of said shell and provided with a hinged cover forselectively closing the outlet.

9. The compressor of claim 7 further comprising second duct means havingan inlet communicating with the outlet of said shell and an outlet beingsufficiently 6 long to mufile the noise produced by said engine and aircompressing means which tends to travel through the duct.

-.-10. The compressor of claim 7 wherein the legs of said first ductmeans and said second duct means extend the entire length of said shell.

References Cited UNITED STATES PATENTS ROBERT M. WALKER, PrimaryExaminer

